Amanda Bynes had a huge bust-up with Paris Hilton at an LA nightclub on Thursday night.
The 28-year-old actress entered 10ak with a male friend and tried to sit at the table of Paris, 33, who was with her pal Brandon Davis.
A witness shared: "Amanda tried to sit at Paris and Brandon's table, and they were not happy about it. There was a scene, and words exchanged, before they kicked her out of their area."
Following the incident, Amanda was seen acting strangely for the rest of the night.
The source told the New York Post's Page Six column: "Amanda wasn't drinking, but she was acting really weird. She stood in the middle of the club with her friend, looking really awkward, and just seemed totally out of it."
Amanda - who was released from a psychiatric facility on October 30 - has reportedly been diagnosed with bipolar disorder and was recently recorded on tape threatening to kill her own parents, Rick and Lynn Bynes.
She said: "I don't want to shoot my father in the face, and that's why I said I want to like strip for him as a joke.
"I want to literally like lead him into a ditch and ... I have't decided how I'd want to murder him, because now I have like this war wound on my face, and I don't believe in murder. Nothing would give me greater pleasure than like, slitting his throat."
TMZ said Amanda's family members wanted the tapes released because they might act as "wake-up call for medical professionals to intervene and get her help".